Download or read book Simulations of Tip Vortex Cavitation Flows with Nonlinear K Model written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Tip Vortex Formation and Cavitation written by Brant Howard Maines and published by . This book was released on 1995 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Computational Modelling for Cavitation and Tip Vortex Flows written by Abolfazl Asnaghi and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book On Simulating Tip leakage Vortex Flow to Study the Nature of Cavitation Inception written by Wesley Huntington Brewer and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Cavitation is detrimental to the performance of ships and submarines, causing noise, erosion, and vibration. This study seeks to understand cavitation inception and delay on a typical ducted propulsor by utilizing the SimCenter's unstructured simulation and design system: U2NCLE. Specifically, three fundamental questions are addressed: 1. What are the macroscale flow physics causing cavitation inception? 2. How does cavitation inception scale with Reynolds number? 3. How can tip-leakage vortex cavitation inception be suppressed? To study the physics of cavitation inception, a ducted propulsor simulation is developed and extensively validated with experimental results. The numerical method is shown to agree very well with experimental measurements made in the vortex core. It was discovered that the interaction of the leakage and trailing edge vortices cause the pressure to drop to a local minimum, providing ideal conditions for inception to occur. However, experimental observation shows that inception does not occur at the minimum pressure location, but rather at the point where the two vortices completely coalesce. At the point of coalescence, the simulation reveals that the streamwise core velocity decelerates, causing the air nuclei to stretch and burst. A Reynolds number scaling analysis is performed for the minimum pressure and maximum velocity in the vortex core. First, the numerical method is validated on a flate plate at various Reynolds numbers to assess the ability of typical turbulence models to predict Reynolds numbers ranging from one million to one billion. This scaling analysis methodology is then applied to the propulsor simulation, revealing that the minimum pressure in the vortex core is much less dependent on Reynolds number than was previously hypothesized. Lastly, to investigate means of delaying cavitation inception, the propulsor is parameterized and studied using design optimization theory. Concepts of vortex alleviation evident in nature are used to suggest suitable parameterizations. Also, dimension reduction is used to reduced the number of design variables. Finally, the concepts are implemented, evaluated, and shown to completely decouple the two vortices causing cavitation inception. Moreover, the minimum pressure in the vortex core is significantly increased.
Download or read book Asymptotic Study of Tip vortex Cavitation written by Alain Bovis and published by . This book was released on 1980 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book On Simulating Tip leakage Vortex Flow to Study the Nature of Cavitation Inception written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Cavitation is detrimental to the performance of ships and submarines, causing noise, erosion, and vibration. This study seeks to understand cavitation inception and delay on a typical ducted propulsor by utilizing the SimCenter's unstructured simulation and design system: U2NCLE. Specifically, three fundamental questions are addressed: 1. What are the macroscale flow physics causing cavitation inception? 2. How does cavitation inception scale with Reynolds number? 3. How can tip-leakage vortex cavitation inception be suppressed? To study the physics of cavitation inception, a ducted propulsor simulation is developed and extensively validated with experimental results. The numerical method is shown to agree very well with experimental measurements made in the vortex core. It was discovered that the interaction of the leakage and trailing edge vortices cause the pressure to drop to a local minimum, providing ideal conditions for inception to occur. However, experimental observation shows that inception does not occur at the minimum pressure location, but rather at the point where the two vortices completely coalesce. At the point of coalescence, the simulation reveals that the streamwise core velocity decelerates, causing the air nuclei to stretch and burst. A Reynolds number scaling analysis is performed for the minimum pressure and maximum velocity in the vortex core. First, the numerical method is validated on a flate plate at various Reynolds numbers to assess the ability of typical turbulence models to predict Reynolds numbers ranging from one million to one billion. This scaling analysis methodology is then applied to the propulsor simulation, revealing that the minimum pressure in the vortex core is much less dependent on Reynolds number than was previously hypothesized. Lastly, to investigate means of delaying cavitation inception, the propulsor is parameterized and studied using design optimization theory. Concepts of vortex alleviation evident in nature are.
Download or read book Numerical Methods for Prediction of Tip Vortex Cavitation Inception written by Monir F. George and published by . This book was released on 1993 with total page 278 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Numerical Modeling of Natural and Ventilated Cavitating Flows written by Qiao Qin and published by . This book was released on 2004 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Cavitation Instabilities and Rotordynamic Effects in Turbopumps and Hydroturbines written by Luca d'Agostino and published by Springer. This book was released on 2017-03-17 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book provides a detailed approach to the physics, fluid dynamics, modeling, experimentation and numerical simulation of cavitation phenomena, with special emphasis on cavitation-induced instabilities and their implications on the design and operation of high performance turbopumps and hydraulic turbines. The first part covers the fundamentals (nucleation, dynamics, thermodynamic effects, erosion) and forms of cavitation (attached cavitation, cloud cavitation, supercavitation, vortex cavitation) relevant to hydraulic turbomachinery, illustrates modern experimental techniques for the characterization, visualization and analysis of cavitating flows, and introduces the main aspects of the hydrodynamic design and performance of axial inducers, centrifugal turbopumps and hydo-turbines. The second part focuses on the theoretical modeling, experimental analysis, and practical control of cavitation-induced fluid-dynamic and rotordynamic instabilities of hydraulic turbomachinery, with special emphasis on cavitating turbopumps (cavitation surge, rotating cavitation, higher order cavitation surge, rotordynamic whirl forces). Finally, the third part of the book illustrates the alternative approaches for the simulation of cavitating flows, with emphasis on both modeling and numerical aspects. Examples of applications to the simulation of unsteady cavitation in internal flows through hydraulic machinery are illustrated in detail.
Download or read book Cavitation and Wake Structure of Unsteady Tip Vortex Flows written by Douglas P. Hart and published by . This book was released on 1993 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Development of a Model for Propeller Tip Vortex Cavitation and Analysis of the Radiated Pressure Fluctuations written by Yasaman Mirsadraee and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Tip Vortex Cavitation Characteristics and Delay of Inception on a Three Dimensional Hydrofoil written by William G. Souders and published by . This book was released on 1981 with total page 59 pages. Available in PDF, EPUB and Kindle. Book excerpt: A research program was conducted to investigate both the fundamental aspects of, and techniques for delaying, tip vortex cavitation on a three-dimensional hydrofoil. The specific concepts considered for delaying tip vortex cavitation included: a bulbous tip, an artificially roughened tip, and a mass injected tip. The experiments were conducted in the David W. Taylor Naval Ship Research and Development Center 24-inch cavitation tunnel, where the effects of the various concepts on both foil tip vortex cavitation inception and performance were established. These measurements were made at a Reynolds number R subscript c, based on root chord length, of approximately 5,000,000. Some of the more fundamental aspects of the tip vortex rollup process have been documented through the use of flow visualization techniques. The results for the tip vortex cavitation delay concepts indicate substantial increases in the tip vortex cavitation inception speed relative to the unaltered tip; i.e., a 94 percent increase for the roughened tip, 38 percent for the bulbous tip, and 54 percent and 33 percent for the active and passive mass injected respectively. These results were obtained over a wide range of foil angle of attack and with little or no measurable loss in foil performance; i.e., no measurable lift decrease or drag increase. (Author).
Download or read book Modeling of Unsteady Wake Alignment and Developed Tip Vortex Cavitation written by Hanseong Lee and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Tip Vortices in Unsteady Flows written by and published by . This book was released on 1992 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report describes in brief the activities of our research in, first, cavitation inception, and them, second, tip vortex problems in steady and unsteady flows. There are two components of this work. The first is an experimental study of cavitation inception and cavitation nuclei determination in a variety of laboratory and natural settings. Cavitation and cavitation inception are important aspects of the complex flow associated with propulsion in the ocean environment. Two specific features of this flow were addressed in a long series of reports and publications listed at the end of this report. These features are (1) cavitation inception processes in a large scale turbulent shear flow and (2) cavitation inception and the structure of trailing tip vortices in first steady and then unsteady flows. Finite aspect ratio hydrofoils were used in both studies; the latter unsteadiness was achieved by oscillating the foil in pitch of a point 35% of the chord from the leading edge.
Download or read book Physical Mechanism and Flow Control of Tip Vortex Cavitation written by Ali Amini and published by . This book was released on 2020 with total page 119 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mots-clés de l'auteur: tip vortex cavitation ; dissolved gas content ; laminar separation bubble ; non-planar winglet ; flexible trailing thread.
Download or read book Computation of Unsteady Internal Flows written by Paul G. Tucker and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt: Computation of Unsteady Internal Flows provides an in-depth understanding of unsteady flow modeling and algorithms. This understanding enables suitable algorithms and approaches for particular fields of application to be selected. In addition, the understanding of the behavior of algorithms gained allows practitioners to use them more safely in existing codes, enabling meaningful results to be produced more economically. Features of Computation of Unsteady Internal Flows: Specialized unsteady flow modeling algorithms, their traits, and practical tips relating to their use are presented. Case studies considering complex, practically significant problems are given. Source code and set-up files are included. Intended to be of a tutorial nature, these enable the reader to reproduce and extend case studies and to further explore algorithm performances. Mathematical derivations are used in a fashion that illuminates understanding of the physical implications of different numerical schemes. Physically intuitive mathematical concepts are used. New material on adaptive time stepping is included. £/LIST£ Audience: Researchers in both the academic and industrial areas who wish to gain in-depth knowledge of unsteady flow modeling will find Computation of Unsteady Internal Flows invaluable. It can also be used as a text in courses centered on computational fluid dynamics.
Download or read book Model for prediction of tip vortex cavitation written by Petter Eriksson and published by . This book was released on 2002 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt:
